The present invention relates to tools and methods for machining and, more particularly, to tools and methods for machining stacked materials having different characteristics.
In the aerospace industry, stacked materials are very common. Materials of particular interest in this industry are materials made of stacked fiber reinforced polymer (FRP)-Ti, FRP-Al, and FRP-Stainless Steel. FRP can be a carbon fiber reinforced polymer (CFRP) or a glass fiber reinforced polymer (GFRP). It is difficult to machine stacked materials when the two materials are best machined by different types of cutting edges. It has generally been necessary to choose between a tool designed for CFRP or a tool designed for, for instance, Titanium. This results in a shorter tool life and poor surface finishes on the workpiece.
Another problem that occurs when machining stacked materials is that sharp chips from a material, such as Titanium, cause scratches on the more delicate material, such as CFRP and GFRP, when being extracted out of the flute of the tool.
DE 20 2011 001512 U1 and JP H06 246525 A each shows a tool that comprises positive and negative pitch angles.
It is desirable to provide a tool and method for machining a stacked material that can provide optimal machining characteristics for the respective materials of the stacked material. It is also desirable to provide a tool and method that reduces the potential for damage to the more delicate material.